etl_code/temperature/CleanReducer.java

import java.io.IOException;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class CleanReducer
        extends Reducer<Text, IntWritable, Text, NullWritable> {
@Override   
 public void reduce(Text key, Iterable<IntWritable> values, Context context)
            throws IOException, InterruptedException {
        context.write(key, NullWritable.get());
    }
}

